Key to Station Model Symbols, for lab 5 PDF

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Download Key to Station Model Symbols, for lab 5 PDF

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Weather Map Symbols

Ci invading sky

Cs below 45°

Cs above 45°; not overcast

Overcast Cs

Cs not ovcercast; not increasing

Cc

2

As

Dense As a/o Ns

Ac; semitransparent

Ac Standing Lenticularis

Ac invading sky

Ac from Cu

Ac with As / Ns

Ac congestus

Ac of chaotic sky

Moderate Cu

Cb no anvil

Sc from Cu

Sc NOT from Cu

St

Stfra or CuFra of bad weather

Cu ans Sc different heights

Cb w/anvil

1

E Cu

1/8th skycover

2/8th 3/8th 4/8th skycover skycover skycover

The lower right area is reserved for the past weather, which is the most significant weather that has occurred within the past six hours excluding the most recent hour. n/a Clear or Few Clouds (not plotted) n/a

Partly cloudy (scattered) or variable sky (not plotted)

n/a

Cloudy (broken) or overcast (not plotted)

5/8th 6/8th 7/8th 8/8th Sky skycover skycover skycover skycover Obscured

998 -03

77 5 71 20

Sandstorm or dust storm, or drifting or blowing snow Fog, or smoke, or thick dust haze Drizzle Rain Snow, or rain and snow mixed, or ice pellets (sleet) Shower(s) Thunderstorm, with or without precipitation

B3 A B2 C DE F G H B1 I J

Calm wind 5 knots 15 knots 20 knots 25 knots 55 knots

Cold Front - a zone separating two air masses, of which the cooler, denser mass is advancing and replacing the warmer. Warm Front - a transition zone between a mass of warm air and the cold air it is replacing. Occluded Front - a composite of two fronts, formed as a cold front overtakes a warm or quasi-stationary front. Two types of occlusions can form depending on the relative coldness of the air behind the cold front to the air ahead of the warm or stationary front. A cold occlusion results when the coldest air is behind the cold front and a warm occlusion results when the coldest air is ahead of the warm front. Stationary Front - a front between warm and cold air masses that is moving very slowly or not at all. Trough - No temperature difference across boundary Dry Line - a boundary separating moist and dry air masses. It typically lies north-south across the central and southern high Plains states during the spring and early summer, where it separates moist air from the Gulf of Mexico (to the east) and dry desert air from the southwestern states (to the west).

Rising, the falling Rising, then steady; or rising, then rising more slowly Rising steadily, or unsteadily Falling or steady, then rising; or rising, then rising more quickly Steady, same as 3 hours ago Falling, then rising, same or lower than 3 hours ago Falling, then steady; or falling, then falling more slowly Falling steadily, or unsteadily Steady or rising, then falling; or falling, then falling more quickly

LWE

AT H E R S

E

I CE RV

NA

A EP

Squal Line - a line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the thunderstorms.

G

This number and symbol tell how much the pressure has changed (in tenths of millibars) in the past three hours and the trend in the change of the pressure during that same period. In this example, the pressure was steady then fell (lowered) becoming 0.3 millibars LOWER than it was three hours ago.

U. S . D

JetStream - An Online School for Weather http://www.srh.noaa.gov/srh/jetstream/synoptic/wxmaps.htm

J

These lines indicate wind direction and speed rounded to the nearest 5 knots. The longest line, extending from the sky cover plot, points in the direction FROM which that wind is blowing. Thus, in this case, the wind is blowing FROM the southeast. The shorter lines, called barbs, indicate the wind speed in knots (kt). The speed of the wind is determined by the barbs. Each long barb represents 10 kt with short barbs representing 5 kt. A pennant is used to represent each 50 kt. In this example, one short barb and one long barb means the wind speed is 15 kt.

Next to the visibility is the present weather symbol. There 95 symbols which represent the weather that is either presently occurring or has ended within the previous hour. In this example, a light rain shower was occurring at the time of the observation.

AA

Dense Ci from Cb

CE NO

Dense Ci

The circle symbol in the center represents the amount of total cloud cover reported in eighths. This cloud cover includes all low, middle, and high level clouds. No Clouds

I

Ci

A TI O

F

3

C

N

H

The number at the lower left is the dewpoint temperature. The dewpoint temperature is the temperature the air would have to cool to become saturated, or in other words reach a relative humidity of 100%.

B

At the upper right is the atmospheric pressure reduced to mean sea level in millibars (mb) to the nearest tenth with the leading 9 or 10 omitted. In this case the pressure would be 999.8 mb. If the pressure was plotted as 024 it would be 1002.4 mb. When trying to determine whether to add a 9 or 10 use the number that will give you a value closest to 1000 mb.

Pressure higher than three hours ago

D

On the second row, the far left number is the visibility in miles. In this example, the visibility is 5 miles.

Along the center, the cloud types are indicated. The top symbol is the high-level cloud type followed by the mid-level cloud type. The lowest symbol represents low-level cloud over a number which tells the height of the base of that cloud (in hundreds of feet) In this example, the high level cloud is Cirrus, the mid-level cloud is Altocumulus and the low-level clouds is a cumulonimbus with a base height of 2000 feet.

Pressure lower than three hours ago

A

In the upper left, the temperature is plotted in Fahrenheit. In this example, the temperature is 77°F.

RT ME

N TO F C OMM

ER

Present Weather Symbols

11

04

State of sky on the whole Clouds generally forming unchanged during past or developing during past hour (not plotted) hour (not plotted)

12

13

05

Visibility reduced by smoke

14

Haze

15

)

Patches of shallow fog at station, NOT deeper than 6 feet on land

Mist

20

21

Drizzle (not freezing) or snow grains, not as shower(s), has ended

30

40

22

Rain (not freezing) not falling as shower(s) , ended in the past hour

31

Slight or moderate dust storm or sandstorm (has decreased in past hour)

(

)

Drizzle, not freezing, intermittent (slight at time of observation)

60 Rain, not freezing, intermittent (slight at time of observation)

70 Intermittent fall of snowflakes (slight at time of observation)

80

41

Slight or moderate dust storm or sandstorm (has begun or increased)

42 Fog in patches

51 Drizzle, not freezing, continuous (slight at time of observation)

61 Rain, not freezing, continuous (slight at time of observation)

71 Continuous fall of snowflakes (slight at time of observation)

81

Rain shower(s), slight

Snow not falling as shower(s) ended in the past hour

32

Slight or moderate dust storm/sandstorm (no change during past hour)

Fog at a distance, but not at the station during the preceding hour

50

More or less continuous shallow fog at station, NOT deeper than 6 feet

Fog, sky visible (has become thinner during preceding hour)

25

26

27

Rain and snow or ice pellets, not as shower(s) ended in the past hour

Freezing drizzle or freezing rain, not as shower(s) ended in the past hour

33

34

Severe dust storm or sandstorm, decreased during the past hour

43

Rain, not freezing, continuous (moderate at time of observation)

72

73

Thunderstorm during past Thunderstorm during past hour w/ slight rain at time hour w/ current moderate/ of observation heavy rain

Continuous fall of snowflakes (moderate at time of observation)

83

Shower(s) of rain and snow mixed, slight

93 Thunderstorm ended w/ current slight snow, rain/ snow mixed, or hail

44

Severe dust storm or sandstorm has begun or increased

45 Fog, sky visible (no appreciable change during the past hour)

54 Drizzle, not freezing, intermittent (heavy at time of observation)

64 Rain, not freezing, intermittent (heavy at time of observation)

74 Intermittent fall of snowflakes (heavy at time of observation)

84

Shower(s) of rain and snow mixed, moderate or heavy

94 Thunderstorm ended w/ current moderate/heavy snow, rain/snow, or hail

Fog, sky obscured (no appreciable change during the past hour)

55 Drizzle, not freezing, continuous (heavy at time of observation)

65 Rain, not freezing, continuous (heavy at time of observation)

75

Shower(s) of snow, or of rain and snow ended in the past hour

36

46

56

Thunderstorm, slight or moderate, w/o hail but w/ rain and/or snow

67

76

77 Ice needles (with or without fog)

86

96 Thunderstorm, slight or moderate, with hail at time of observation

Fog, depositing rime ice, sky visible

59 Drizzle and rain, moderate or heavy

69 Rain or drizzle and snow, moderate or heavy

Rain or drizzle and snow, slight

79 Isolated star-like snow crystals (with or without fog)

88

Shower(s) of snow pellets Shower(s) of snow pellets or small hail, slight with or or small hail, moderate or without rain or rain/snow heavy w/ or w/o rain/snow

Thunderstorm, heavy, w/o hail but with rain and/or snow

Fog, depositing rime ice, or ice fog, sky obscured

Drizzle and rain, slight

Snow grains (with or without fog)

97

Heavy blowing snow (generally above eye level)

49

78

87

Snow shower(s), moderate or heavy

Slight or moderate blowing snow (generally above eye level)

68 Rain, freezing, moderate or heavy

Thunderstorm (with or without precipitation) ended in the past hour

39

58 Drizzle, freezing, moderate or heavy

Rain, freezing, slight

Snow shower(s), slight

95

57

66

Fog or ice fog ended in the past hour

48

Fog, sky obscured (has begun or has become thicker during past hour)

Funnel cloud(s) and/or Tornado(es) during the preceding hour

29

38

Heavy drifting snow (generally below eye level)

Drizzle, freezing, slight

Continuous fall of snowflakes (heavy at time of observation)

85

Shower(s) of hail, or of rain and hail ended in the past hour

47

Fog, sky visible (has begun or has become thicker during past hour)

Squall(s) within sight during past hour

28

37

Slight or moderate drifting snow (generally below eye level)

19

98 Thunderstorm combined with dust storm or sandstorm

Ice pellets (sleet)

89

Shower(s) of hail, slight, w/ or w/o rain or rain/ snow mixed, no thunder

99 Thunderstorm, heavy, with hail at time of observation LWE

AT H E R SE

R

NA

VI C E

U. S . D

A EP

JetStream - An Online School for Weather http://www.srh.noaa.gov/srh/jetstream/synoptic/wxmaps.htm

Shower(s) of rain ended in the past hour

35

Severe dust storm or sandstorm, has no change during past hour

Fog, sky obscured (has become thinner during preceding hour)

Rain, not freezing, intermittent (moderate at time of observation)

Shower(s) of hail, w/ or w/o rain or rain/snow, no thunder, mod. or heavy

18

24

63

92

17

23

62

91

()

( )

Well developed dust whirl Dust storm or sandstorm and/or sand whirl but no within sight or at the dust storm/sandstorm station during past hour

Thunder heard, but no precipitation at the station

Drizzle, not freezing, continuous (moderate at time of observation)

90

16

09

Dust or sand due to wind at or near the station but no dust whirl/sandstorm

Precipitation within sight, reaching the surface within 3 miles

Drizzle, not freezing, intermittent (moderate at time of observation)

Rain shower(s), violent

Widespread dust in the air, not raised by wind at or near station

08

Precipitation within sight, reaching the surface, but more than 3 miles away

53

Intermittent fall of snowflakes (moderate at time of observation)

) (

07

Precipitation within sight, but NOT reaching the ground

52

82

Rain shower(s), moderate or heavy

Lighting visible, no thunder heard

06

- N OA A

10

Clouds generally becoming less developed (not plotted)

03

RT ME

CE

Cloud development NOT observed during past hour (not plotted)

02

A TI O

01

N

00

N TO F C OMM

ER...